VAST error codes / Linear and media errors
VAST error 405: Problem displaying media file
Short answer: A supported MediaFile was found but the player failed to display it.
Debug this tag now
If you only have a live URL, test it first. If the failure is in the wrapper chain, inspect each hop. Validate resolved XML when you already have the response.
What your player reported
405· Problem displaying MediaFile. Media player found a MediaFile with supported type but couldn’t display it. MediaFile may include: unsupported codecs, different MIME type than MediaFile@type, unsupported delivery method, etc.
Wording from the IAB VAST 4.3 specification error table. Players may shorten or reformat it, but the code is the same.
What it means
The player picked a media file of a supported type but still could not play it: a codec, container, or metadata mismatch.
Common causes
- Unsupported codec inside a supported container
- MIME `type` that does not match the actual file
- Corrupt file or wrong reported dimensions/bitrate
How to fix it
Verify the declared `type` matches the real media, and that the codec is supported on the target device. Common in CTV and SSAI trafficking.
VAST error codes are runtime buckets emitted by the player. They tell you where the failure happened, not which line of XML caused it. Paste the raw tag into the validator to map this code onto the exact element and rule.
Related vastlint rules
- VAST-2.0-mediafile-type: <MediaFile> must have a type attribute
- VAST-2.0-mediafile-dimensions: <MediaFile> must have width and height attributes
Related error codes
Debug this tag now
Validate the XML, follow the wrapper chain, or check it in CI before launch:
# CLI: exits non-zero on errors, ideal for pipelines
vastlint check creative.xml